Rotating actuators are used in a large number of devices. Often, in a non-activated state of the actuator, undesirable torsion of the output element must be prevented. In principle, this could be carried out by means of an additional actuator, for example, an electromagnetic brake. However, such an additional actuator is linked with undesirable costs and weight. A self-locking member could also be provided in the drive chain of the actuator, for example, a trapezoidal thread spindle. Such a self-locking member, however, impairs the overall level of efficiency of the actuator.